> If browser F is worse at battery life than browser S, people will figure that out and adapt for themselves.

Unfortunately, the makers of a certain browser also control several major web properties, and regularly make 'mistakes' that break compatibility with competing browsers, while releasing a set of apps that 'forget' users' browser selections on a monthly basis.

Personally, I'd much prefer apple allowed a browser engine with proper ad blocking support. But I do worry that the moment they do so, the almost-monopoly browser market would become a total monopoly.